Mounts for transparencies and the like



March l, 1960 l. c. RINN y 2,926,443

Moum's Foa TRANSPARENCIES, AND THE LIKE Filed Jan. 12, 1956 Irwin C Rinn, Wm.

Unitfd Se@ ,Paw O MOUNTS FOR TRANSPARENCIES AND THE LIKE Irwin C. Rinn, Libertyville, Ill. Application January 12, 1956, Serial No. 558,742 4 Claims. (Cl. 40-158) This invention relates to improvements in mounts for transparencies, and the like. Mounts incorporating the present improvements are well adapted for use with such transparencies as developed X-ray lfilms, and photographic reproductions in general, but I do not intend to limit the use of the mounts herein disclosed to these particular purposes, except as I may do so in the claims to follow.

The mounts herein disclosed are of what may be termed the two thickness or layer type-that is each mount of the present type is generally formed from only two thicknesses of the sheet material of which it is composed, usually paper stock of a meditun degree of compactness. These two layers are conveniently joined together on a fold line, being provided with companion apertures which come into registry when such two layers are folded together to bring their proximate faces into contact over an area which at least partially surrounds the transparency placed between the two` layers and across the registered apertures. The apertures are of size to expose only the picture area of the transparency to view, and to the beam of light of a projector, the conventional transparency being provided with a narrow border of external perimeter larger than such picture area. When the two layers are brought together the, border portion of the transparency should be retained between the marginal portions of the layers surrounding the apertures, thus providing a proper holding effect for the transparency and concealing such non-picture border portion, -but without concealment of the picture portion of the transparency itself. It is thus evident that when assembling the transparency into the mount it is very important to ensure exact registry of such transparency with the apertures, and to hold the transparency in such exactly registered location during the completion of the mount assembling operation. It is also very important to ensure that the introduction and assembling of the transparency border portion between the proximate surfaces of the two layers of the mount shall not result in production of the nal assembly having an over-thickness of noticeable magnitude. Primary objects of the present invention are to attain these results.

Conveniently I shall refer to the -two layers of the mount as its panels The cementing agent used for adhering the proximate surfaces of the two panels together may conveniently be of that type in which a non-tacky material, applied to the surfaces to be adhered together (or to one of said surfaces) becomes tacky and adherent between the proximate surfaces under application of heat and pressure when the surfaces have been registered. I do not limit myself to the use o-f such heat and pressure type of material, except as I may do so in the claims to follow. -Usually, however, some degree of pressure should be applied to force the panels together at the time of, or during the cementing operation to ensure good, even, and iirm cementing over the intended area. When the two panels are thus cemented together the pressure should be applied 2,926,443 Patented May. 1, 1960 areas. This requires that no pressure be applied over that area which will receive the transparency (whether such transparency be present at the time of cementing, or be afterwards inserted into the previously assembled mount). I have herein disclosed mounts of such construction as to attain these objectives.

When the mounted transparencies are to be completely produced in the original assembling operation (that is, when the two mount panels are to be cemented together with the transparency in place between them and in proper registry with the apertures) it is necessary to exactly locate the transparency with respect to such aperture of one panel (the bottom panel of the pair during the assembling operation), and then bring the other or top panel into place with respect to the lower panel and the transparency, and to retain all of said parts in such registered condition during the cementing operation. It is thus evident that slight mis-registry of the transparency with respect to the aperture of the lower panel will result in production of an unacceptable unit. lt is a prime object of the present invention to provide means to ensure exact placement of the transparency with respect to or on or into the lower panel, so as to ensure exact registry when Vthe two pane-ls are brought together and cemented after such transparency placement. lt is a further and important object of the invention to provide such registration ensuring means of a type such that the operation of setting the transparency into or onto the lower panel can be very quickly performed by inexpert manual operations, not requiring the use of highly skilled help in this operation.

yIn connection with the attainment of the foregoing objective I have provided one or more abutments into or against which the transparency is set in order to exactly position such transparency with respect to the lower panel. This or these abutments is or are conveniently formed on or as a portion of the lower panel itself. Such abutments are of such form and so located that they position the transparency in both its lengthwise dimension and its crosswise direction on the panel. Generally the mount will be formed in such manner that its line of fold extends normal to the major axis of the transparency, and the setting of the transparency into or onto the lower panel will be performed by insertion movement of the transparency in direction towards the line of fold and parallel to the major axis of the transparency. During this operation the transparency is positioned laterally to correct register of its sides with respect to the aperture. The termination of such inserting movement should occur at exactly the correct point to bring the lead end of the transparency into register with the Vfar end of the correct position to be occupied by the transparency. Therefore I have provided an abutment or abutments at such far end position to be reached during the transparencies insertion so that the inserting movement will be positively arrested at the correct position with respect to the lower panel. Lateral abutments are also provided on the lower panel for ensuring correct registration of the transparency laterally onto or into the lower panel.

According to my present invention I subject at least one of the panels, generally the lower one, to a die forming and material compressing operation in which the aperture is cut out and in which the material of the panel is subjected to a compressive force by a portion of the die,

so as to compress and depress an area of the panel around Y o ness of the transparency film is within the thickness of over the full areas to be cemented together, but only said such panel, and without increase of the total thickness of theentirely assembled mountV and film. The ability to produce this result will be apparent from the following.

The thickness of the paper stock material conventionally used for such mounts is approximately 0.020 (twenty thousandths of an inch). The thickness of the film conventionally used is approximately 0.005 (five thousandths of an inch). Accordingly, it is possible to compress that portion of the panel material which provides the border support for the film transparency by some amount less than 0.015" (fifteen thousandths of an inch), and without completely penetrating the panel stock at the area of such compression. In fact, a compression of such arca by the amount of slightly more than five thousandths of an inch will produce the needed area to accommodate the border portion of the film transparency, and thus allow the companion or upper panel of the mount to be set flat and smoothly onto the lower mount panel. Thus finaliy the assembled mount with the film transparency in place is of a thickness substantially equal to that of the two panels alone. The cementing together of the two panels will be performed according to the principles already stated hereinbefore.

Due to the fact that the conventional thickness of the mount material is substantially 0.015 greater than the conventional thickness of the film transparency it is also possible, during the die compressing operation by which the film border area sustaining area is produced, to actually compress that portion of such area even more than necessary to receive and accommodate theV lms thickness, so that a deeper and more apparent abutment is there produced to assist in the registering of the` film into correct position prior to setting the upper mount panel down against the lower panel for sealing by cementing. When using this detailed embodiment of my present invention the compressed and depressed area of the lower panel may taper from ak small initial depth at the'near end of the panel to a maximum depth at the far end of the panel (nearest to the line of fold). Of course the extent or degree of compression which will then be produced in the paper stock will be greater at the far end than at the near or film insertion end, and the compressive force needed to effect such greater degree of compression at such far end will be correspondingly greater than at the near end. It is noted, however, that such greater degree of compressive force needed per square inch of exposed area is needfully exerted over only a portion of the total area of the border around the aperture, so the total compressive force is not greatly increased over that amount which would be otherwise needed.

It thus appears that a further feature and object of my present invention is to provide a construction in which the far abutment portion against which the film transparency is arrested during the operation of insertion may be of a maximum depth consistent with the thickness of the paper stock material used.

It is noted that the paper stock conventionally used for such mounts is of a rather medium soft or non-hard texture, so that the needed compression may be pro? duced without need of exerting excessive die pressures. It is further noted that the dies used for producing the so formed panel may preferably be formed to produce sharp cutting effects around the periphery of the compressed area and to a depth greater than the body of such compressed area. Thus a sharp and fully acceptable abutment is produced comprising a portion, at least, of the compressed area, and comprising the abutment against which the film transparency is moved and by which such transparency is exactly positioned.

It is also noted that the paper stock used in these operations should be relatively non-elastic and one which will retain its so-compressed condition after the die pressure has been removed, to an extent which will ensure permanent presence of the desired abutment or abutments.

As an example of such a paper stock material which may principles herein disclosed I mention what is known as Rinn Special F.D. Blue Gray Cover Stock. This weighs approximately 26.2 pounds per hundred sheets, the sheets being of size approximately 261A; inch by 40% inch width and length. These sheets are of thickness of 0.010 inch (ten thouandths of an inch). In the case of sheets of substantially 0.020" thickness the weight per square foot of exposed area would be substantially twice as great as that for such thinner sheets, and the weight per hundred sheets would be approximately 52.4 pounds per hundred sheets of the size referred to above.

Other objects and uses of the invention will appear from a detailed description of the same, which consists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawing:

Figure 1 shows a face or plan view of a blank for the two panels of a film mount embodying the present invention, prior to folding said blank on its central transverse line to bring the two panels together face to face; and in this figure both panels have been die formed and compressed to produce the companion apertures which will come into registry when the blank is folded on its center line and to produce the depressed transparency border Vreceiving area; and the die compressed area of the right-hand panel is defined by a line surrounding said area; and this figure also shows by the dashed line at the right-hand portion of the figure the form of a mask sheet which may be used to prevent the area of the cement agent covered by such mask from being adhered sheet to sheet, to leave an uncemented area forming a thin slit through which lthe transparency may be introduced into the mount after said mount has been otherwise completed, the stippling indicating the surface areas which are coated with the cementing agent;

Figure 2 shows a longitudinal section taken on the line 2-2 of Figure l, looking in the direction of the arrows; and this figure is on enlarged scale as compared to Figure 1; such enlargement being greatly exaggerated in the direction of the thickness of the sheet;

Figure 3 shows a face view of the assembled and completed film mount formed from the blank of Figure 1 when the'film transparency is sealed into the mount at the time of the assembling and cementing operations;

Figure 4 shows a longitudinal section taken on the line 4-4 of Figure 3, looking in the direction of the arrows, but on enlarged scale;

Figure 5 shows a face or plan view of a modified form of blank in which the heat and pressure or other cementing material is left off from that area of the right-hand portion of the blank which should constitute a transparency introducing opening when it is desired to introduce the transparency into the otherwise completed blank as an after-operation; Figure 2 may also be considered as a section taken on the line 2 2 of Figure 5 since the thickness or" the cementing material is not shown in the section of Figure 2;

Figure 6 shows a longitudintal section taken on the line 6--6 of Figure 7, looking in the direction of the arrows; and this yfigure differs from Figure 4 in the sense that in Figure 6 the right-hand proximate surface portions of the two panels are not cemented together, whereas they are cemented together in Figure 4;

Figure 7 shows a face or plan view of the assembled and completed film mount formed from the blank of Figure 5, or from the blank of Figure l when the mask is used `during the forming of the completed mount to prevent cementing together the proximate faces of the' two panels at the location of introduction of the transparent film when such film is introduced into the otherwise completed mount;

Figure 8 shows a fragmentary section taken on the line S- of Figure l, looking in the direction of the arrows, and when the mask sheet is set into placeV to prevent vcementing together 'the proximatej faces of' the two panels at the location of introductionof the afterwardsj to-be-inserted transparency;

Figure 9 shows a longitudinal section similar to that of Figure 2; but in the case of Figure 9 the blank has been die-treated to produce compressed border areas around the apertures of`both panels, which compressed areas register with each other when the panels are folded into facial contact to produce a combined border area of double thickness, or of the originally explained thickness but by use of compressions of one-half extent in each panel; y

Figure 10 shows a section'through an assembled and completed mount made from the blank of Figure 9, it being noted that the transparency included in this embodiment is located exactly on the medial plane, that is, the plane of contact between the two panels;

Figure 1l shows a section through another modified form of mount in which the depressed area produced in one of the panels is deeper at the far end (measured from the point of transparency introduction) than at the near end (closest to the point of transparency introduction) thus producing a deeper abutment against which the leading edge of the transparency film will engage at its limited position; and in this figure the right-hand portion of the transparency film is shownas being compressed slightly into the proximate surface of the upperpanel by a compressing operation produced duringthe heat and pressure cementing operation, or otherwise; and

Figure 12 shows on greatly exaggerated scale of thickness'the section through a fragment of the panel at the location of one end of the compressed area; and this figure also shows typically the relative thickness dimensions of the panel, the film transparency, and the form of compressed areas end, and the fact that the border of the compressed area is sharply defined by the die cutting and forming operation.

Referring to the drawing, in Figure 1 I have shown the two panel blank having the right-hand and the lefthand panel sections 21 and 22, respectively. This blank is shown as provided with the transverse fold line 23 across the middle so that by folding the blank on this line the two panels are brought together face to face, the top or previously exposed faces coming together. These panels l are provided with companion apertures 24 and 25 which are so disposed in the two panels that when the panels are thus folded together said apertures exactly register with each other. These apertures are of shape and size to correspond to the picture portion of a lm transparency which is to be set into and carried by the mount.

The blank is formed of stock, preferably paper stock, of somewhat compressible nature and composition, so that under die produced pressure portions of the areas of the'panels may be compressed to permanently reduce the thickness of the panels and correspondingly increase the density of the panel material at the compressed area. Such so-compressed area must then remain in its compressed condition sufliciently to ensure the retention of the desired transparency accommodating depression and the abutment or abutments to which I have already referred. One such material has already been' disclosed herein.

'In Figure 1 I have shown the panel 21 as having the thus depressed perimeter area 26 surrounding the aperture 24. This depressed border area is of width in each of its linear portions to receive the corresponding portion of the border of the iilm transparency when such transparency is set into the depression, so that such depressed area will serve to accurately locate the film transparency with respect tothe aperture and correctly expose only the picture portion of the filmat the aperture. Also, the depth of the depressed area is preferably approximately the same as the thickness of the lm, so that said film, when so located on such border area and registered with the aperture will have its upper face substantially in planar registry with the top face of the panel.v A slight andere clearance between the edges of the lm and the perim7 eter of the" border area is, however, desirable to allow for slight expansion and contraction of the film with respect to the panel. Such changes occur with the heating and cooling of the lm when the mount is used in a projector or the like.

In the forming of the so-prepared blank with its two panels use may be made of a conventional cutting and forming die of such form as to cut out the two apertures during one portion of the die stroke, and the production of the depressed and compressed area 26 during either the same or another portion of such stroke. Sufficient pressure will be exerted on such die to produce the desiredrcompressing and depressing action in the righthand panel 21, according to the nature and density and other characteristics of the blank material. It is preferred that such die be so formed that the outer perimeter defining edge of the depressed and compressed border area 26, which outer perimeter is designated 27, be sharply cut down to a depth somewhat greater than the reduction in thickness of the major portion of the depressed border area, as well shown at 28 in Figure 12, but the operation should be so conducted and proportioned that the panel is not cut clear through by such operation. By thus conducting the operation it will be found that a sharply defined, substantially even and smooth wall or surface will be provided surrounding the depressed border area, vand against which the edge of the film may contact in order to exactly register the film in its intended location with respect to the aperture. Furthermore, this operation will ensure that the full border area is brought to the desired degree of compressed reduction'in thickness to ensure a smooth surface on which the border of the film will seat when the lm is set into its intended location within the right-hand panel.

The proximate faces of the two panels are cemented or adhered together after the panels have been brought into folded relationship. The cementing agent may be of any type and characteristics found to firmly adhere the two panels together without damage to the film, and depending on the texture and composition and finish of the panel stock. Generally some form of heat and pressure responsive adherent will be used, many of which are'now available for this and similar purposes. However, the adherent is usually applied to the entire surfaces of both of the panels 21 and 22 prior to producing the die-cutting and forming operations. Accordingly, the entire surface of the panel 21 is also thus originally coated with such adherent. Such being the case it is evident that the border area 26 is also coated with such adherent when and after the die cutting and forming operations have been performed. As previously shown, when the film has been set into place in the depressed border area 26 and the panel 22 has been folded over the panel 21, the adhering or cementing operation must be performed in such manner that such adherent present on the floor of the depressed area 26, and also present on the opposite areas of the panel 22 (that is, surrounding the aperture of that panel to a Width corresponding at each point to the width of the border area 26) shall not be adhered to the non-picture border portion of the transparency. Such non-adherence of the border area of the film is very important since thereby the film is left free to expand and contract slightly with changes of temperature and without buckling of the film. Such changes of temperature are large in the case of transparencies to be used in projectors which use strong beams of light produced by incandescent lamps. Accordingly, when the adherent is of the heat and pressure type the pressing dies o-r clamps used to effect the adhering operations must be of such form as not to apply pressure nor heat to such border areas of the panels so that when the the adhering operation has been completed all portions of the panels will be adhered together with the exception of such border areas (and also with the exception of an area extending from such border area to the edge of the mount through which the transparency may be introduced or removed when such 'arrangement is desired). In case the cementing agent should not be originally applied to the border areas it would, of course, not be necessary to take the precaution just explained against producing any adherence over such areas. It is evident that when the foregoing operation of producing adherence over all areas except those of said border areas is completed the transparency will be retained within its proper location and in registry with the apertures, but that it will be free to slightly adjust itself for expansions and contractions produced by the heating and cooling effects of the projector when the mount is used in such a device.

In Figure 1 I have shown the cementing agent as being applied completely around the aperture and border areas, including the right-hand marginal. portion 29. When such a right-hand marginal portion 29 is thus provided with the cementing agent it is evident that after the assembling and cementing operations have been completed the film will be completely encased within the mount and locked therein against removal except by damaging the mount itself. Sometimes it will be desired to produce mounts themselves, incorporating features of the present invention, but into which the transparencies have not been assembled prior to the cementing operations. In such cases the mounts may be used to-receive transparencies intro-duced after such cementing operations have been completed. vIt may also be desirable, in such a case, to cement the so-after-introduced transparency into its mount and against later removal. I have herein disclosed modifications by which these operations may be performed, as follows:

In Figure 1 i have shown, by dashed lines 30 the general size and configuration of a mask sheet of thin material laid over the area 29 previously referred to. This mask should be of material to which the cementing agent will not adhere even under the application of heat and pressure, and a material which can be readily pulled away from between the two panels after the cementing operation has been completed. By use of such a mask the two panels may be brought into facial contact without the presence of the transparency, but with the mask set into the location shown in Figure l. Then the application of heat and pressure, or other adhering operation, will cement the two panels together but leaving the area 29 uncemented to the companion area of the panel 22.V

Thus a slitted opening will be left between the two panels through which the transparency may be inserted into place after the mount has been otherwise completed. Having thus inserted the transparency into the otherwise completed mount said transparency may be sealed in place by application of heat and pressure (or other cementing operation) to the exposed surface of one of the panels over the location of the area 29. This type of construction will make it possible for the purchaser of such mounts to use them for protecting and mounting his own transparencies should he desire to do so.

Again, in Figure 5 I have shown the area 31 of the right-hand panel as a plain area, devoid of the cementing or adhering agent over a width of the mount corresponding to the width of the to-be-inserted transparency. With this type of construction the completion of the mount by cementing together the stippled areas of Figure 5 except the border portion 26 will leave an uncemented or nonadhered area through which the transparency may be inserted or removed since said area will not be sealed at any time. Generally it will be found that the seating of the transparency into the depressed and compressed border portion of the panel 21 will be sufficient to retain the transparency in place without other retaining means, especially when. the two panels are formed of material which is capable of retaining its fiat condition against expected deformations due to ordinary handling of the unit.

It is to be noted that when the depressed area is formed only in one panel, as thus far disclosed, the location of the transparency is slightly to one face of the completed mount-that is, the transparency is not exactly in the medial plane of the completed mount. Furthermore, all of the compressing operationv to produce the compressed area 26 of Figure 1 is performed on one of the panels, so that a correspondingly high compressive force must be developed to compress thematerial of such single panel sufficiently to produce the depth desired for the border 26. Such total force is greater than the force needed to effect compression to only one-half of the desired depth of such border. In Figure 9 I have shown a longitudinal sectionV through another modified form of mount in which each of the panels is provided with a compressed and depressed border area, but to a depth of substantially only one-half that of the border required in the previous embodiment of the invention. Thus, in Figure 9 these are the depressed and compressed portions 32 and 33. They are so located that when the blank is folded into its intended mount producing form these areas come into registry as shown in Figure 10. In that figure the transparency is seen to be located within the medial plane of thecompleted mount.

It is observed that when using the modification just described'the depressions and compressions are only onehalf the depth provided in the former embodiments of the invention. Accordingly, the depth of shoulder of each panel to which shoulder the inserted film or other transparency is set during the assembling operation is small and the benefits of such shoulder as a film registering element which may be dependably used during rapid operations is impaired. In Figure 1l I have shown still another modification in which the depressed and compressed area is of varying depth measured from the point of film insertion to the final resting place of the film; that is, this border portion is a-rnaximumV depth at its far end 33a, and of least depth at its near end 34. During the assembling operations, and before the upper panel has been folded down into facial engagement with the lower panel the ilm is set into place against the defining abutments produced by the borders of the depressed and compressed area. To do this the film is quickly moved from the insertion edge of the panel towards the fold line. In doing this the leading edge of the film should be caused to slide over the face of the panel 21 until such leading edge is arrested by engagement with the abutment presented by the edge of the depressed border portion at the far location. If that abutment is not sufficient in depth or vertical dimension the edge of the transparency may over-ride such edge, requiring a second or even a third inserting operation to bring about the correct registry.

In the embodiment shown in Figure 11 the depth of the depressed border at the far end (nearest the fold line) is a maximum consistent Wtih the thickness of the material being used for the blank, and thus a most effective abutment is provided. It is noted that when using this embodiment of the invention the compressive force needed to etect the deep compression at the end 33 is quite large; but conversely, the force needed to effect the compression at the end 34 is small. Accordingly, the total force which must be applied to the die in the case of production of the embodiment shown in Figure l1 is not greatly in excess of that force needed in the cases of the other embodiments. When using the embodiment shown in Figure ll the depth of the depressed area at the near end 34 may be so small as not to take care of the actual thickness of the transparency in which case a portion of the transparency will project above the surface of the panel 21 as shown in Figure l1. However, in such a contingency the compressive force exerted between the two panels during the cementing and adhering operation under heat and pressure (or otherwise) will be sufficient to effect a slight compression of the material of the panel over that area where needed to bring the outer surfaces of the two panels into parellelism. Such a condition is shown in Figure 11. Of course, in that figure, as well as the other sectional views, the thickness values have been greatly exaggerated, so that in actuality the transparency will to all practical purposes lie substantially parallel to the outer surfaces of the mount. l

I claim:

l. As a new -article of manu-facture, a mount to re-l ceive and retain a transparency having a picture area and a surrounding nonspicture carrying border, said'mount comprising a blank of permanently compressible substantially non-elastic paper-stock like material foldable on a fold line extending across the central portion of the blank, the blank sections at the sides of said fold line comprising companion panels and the blank being foldable to bring the proximate surfaces of said panels into facial engagement with each other .to produce a mount of double the thickness of the blank, said panels being provided with companion apertures so located that when the panels are in facial engagement the perimeters of said apertures register with each other, said apertures being of substantially the same size and contour as the picture area of the transparency to be received and retained in said mount, and a permanent depressed border area of at least one panel surrounding the aperture of said panel and extending from the aforesaid proximate surface of said panel towards the opposite surface of said panel for a depth thickness o-f the transparency, -s-aid opposite .surface of said panel being substantially flat and all portions of said surface including .those surface areas opposite to the depressed border area lying within a common plane, said permanent depressed border area having a perimeter of substantially the same size and form as the perimeter of the edge of said transparency to accommodate the border portion of said transparency seated at least partially within said depressed border portion of the panel and with the picture area of the transparency registered with the aperture of said panel when the edge of .the transparency is contained within the perimeter of the depressed border of the panel and when said transparency edge is substantially in engagement with said depressed border perimeter, the depth of the depressed -fborder being at all points less than the thickness of the panel and the panel material below the lborder floor at each point of said de- 'pressed lborder being permanently compressed by an amount equal to the depth of said border at such point, and said depressed border portions having a density greater than the density of the non-compressed portions of the panel by .an amount substantially equal to the density of the non-compressed portions of the panel multiplied by the thickness of such non-compressed portions and divided by the thickness of the compressed border floor portions, and cementing agent vadhering the proximate sur-` faces of the panels together over selected areas of said surfaces other than said surface areas which are in registry with said depressed border areas, wherein Ithe depth of the depressed border is greater in some areas of.A said border than in other areas thereof, and wherein the depth of the depressed border changes regularly at points of said border located at regularly progressing distances from the fold line of the blank.

2. An article as defined in claim 1, wherein the depth of the depressed border is greatest in its points which are closest .to said fold line of the mount.

3.` As a new article of manufacture, a mount to receive and retain a transparency having a picture area to accommodate at least a portion of the and a surrounding non-picture carrying border, said mount comprising a blank of permanently compressible substantially non-elastic paper-stock like material foldable on a fold line extending across the central portion of the blank, the blank sections at the sides of said fold line comprising companion panels and the blank being foldable to bring the proximate surfaces of said panels into facial engagement with each other to produce a mount of double the thickness of the blank, said panels being provided with companion apertures so located that v when the panels are in facial engagement the perimeters of said apertures register with each other, said apertures being of substantially the same size and contour as the picture area of the transparency to be received and retained in said mount, and a permanent depressed border area of at least one panel surrounding the aperture of said panel and extending from the aforesaid proximate surface of said panel towards the opposite surface of said panel for a depth to accommodate at least la portion of the thickness of the transparency, said opposite surface of said panel being vsubstantially at and all portions of said surface including those surface areas opposite to the depressed border area lying within a common plane, said permanent depressed border area having a perimeter of substantially the same size and form as the perimeter of the edge of said transparency to accommodate the border portion of said transparency seated at least partially within said depressed border portion of the panel and with the picture area of the transparency registered with the aperture of said panel when the edge of the transparency is contained within the perimeter of the depressed border of the panel and when said transparency edge is substantially in engagement with said depressed border perimeter, the depth of the depressed border being at all points less than the thickness of the panel and the panel material below the border oor at each point of said depressed .border being permanently compressed by an amount equal to the depth of said border at such point, and said depressed border portions having a density greater than the density of the non-compressed portions of the panel by an amount substantially equal to the density of the non-compressed portions of the panel multiplied by the thickness of such non-compressed portions and divided by the thickness of the compressed border oor portions, and cementing agent adhering the proximate surfaces of the panels together over selected areas of said surfaces other than said surface areas which are in registry with said depressed border area, wherein the perimeter of said permanent depressed area comprises a surface lying at substantially right angles to the surface of the panel, and extends to a depth lower than the surface of said depressed border area which is not in engagement with such perimeter.k

4. An article as dened in claim 3, wherein said perimeter surface comprises the exposed cut portion of the ynon-depressed material of thepanel wherein such depressed border area is contained.

References Cited in the le'of this patent UNITED STATES PATENTS 2,341,467 Nedell Feb. 8, 1944 2,390,053 Bradford Dec. 4, 1945 2,495,142 Seary Jan. 17, 1950 2,505,250k Kime Apr. 25, 1950 2,512,106 Langan June 20, 1950 2,656,631 Cadwell Oct. 27, 1953 

